124 ANCIENT PLANTS 



Thus it can be seen at a glance, without entering 

 into minutice, that the characters are divided between 

 the two groups with approximate equality. The con- 

 nection with Ferns is clear, and the connection with 

 Gymnosperms is clear. The point which is not yet de- 

 termined, and about which discussion will probably long 

 rage, is the position of this group in the whole scheme 

 of the plant world. Do they stand as a connecting link 

 between the ferns on one hand and the whole train of 

 higher plants on the other, or do they lead so far as the 

 Cycads and there stop? 



CHAPTER XIII 



PAST HISTORIES OF PLANT FAMILIES 

 VI. The Ferns 



Unfortunately the records in the rocks do not go 

 back so far as to touch what must have been the most 

 interesting period in the history of the ferns, namely, 

 the point where they diverged from some simple an- 

 cestral type, or at least were sufficiently primitive to 

 give indications of their origin from some lower group. 



Before the Devonian period all plant impressions 

 are of little value, and by that early pre-Carboniferous 

 time there are preserved complex leaves, which are to 

 all appearance highly organized ferns. 



To-day the dominant family in this group is the 

 PolypodiacecB. It includes nearly all our British ferns, 

 and the majority of species for the whole world. This 

 family does not appear to be very old, however, and 

 it cannot be recognized with certainty beyond Mesozoic 

 times. 



From the later Mesozoic we have only material in 

 the form of impressions, from which it is impossible to 



